1. Technical Field.
This invention generally relates to
electrical circuits for activating peripheral devices responsive to a parent device power up, and in particular this invention relates to an electrical circuit which only activates the peripheral device responsive to increased activity of the parent device.
2. Background Art.
There are many situations in which it is advantageous to delay activation of peripheral devices until after the parent device is powered up and has attained a quiescent state. A typical situation is that of a personal or business computer system where the activation of the monitor, disk drives, printers, etc. are delayed until after the computer itself is fully on-line.
MIONE, U.S. Pat. No. 4,675,537, teaches an outlet strip which contains an intelligent outlet from which the computer or parent device is supplied. Upon activation of the parent device, the intelligent outlet will delay activation of the outlets supplying the peripheral devices until the parent device has had time to attain a quiescent operating state. The outlet strip is especially helpful in eliminating undesirable transient currents and random logic states caused by simultaneous power up of the parent and peripheral devices.
In any given computer system, the computer and monitor generally have very similar duty cycles while a disk drive would typically have a substantially smaller duty cycle and a printer or paper stacker would demonstrate yet even a smaller duty cycle. Disk drives and printers are relatively quiet when not being addressed by the computer. A paper stacker, however, is quite loud and annoying to the computer operator in its quiescent state.
It should be readily apparent that the smart outlet power strip of Mione does not provide an adequate solution to this problem, because the paper stacker will remain on essentially the entire time the computer is on. Besides being loud and annoying, allowing the paper stacker to remain on when not in use substantially decreases its life expectancy. Heretofore, the solution to this problem has simply been for the operator to manually switch the paper stacker on and off as necessary. This is obviously a great inconvenience to the computer operator. Further, a great deal of operator time is consumed running back and forth to switch the paper stacker on and off.
What is needed is an electrical circuit for activating a peripheral device, e.g. a paper stacker, responsive to increased activity of the parent device, which is in this case, the cooperating computer printer.
It is therefore an object of the present invention to provide an electrical circuit which is capable of detecting a current surge in the power line of the parent device and activating the peripheral device in response thereto.